Process for removing naphthalene from gases



Nov. 28, 1933. w. MUHLENDYCK 1,937,460

PROCESS FOR REMOVING NAPHTHALENE FROM GASES Filed Feb. 18, 1931 PatentedNov. 28, 1933 UNITED STATES PATENT OFFICE Wilhelm Miihlendyck, Dortmund,Germany Application February 18, 1931, Serial No. 516,821, and inGermany February 19, 1930 7 Claims.

This invention relates to a process for removing naphthalene from gases.

The gas produced during the dry distillation or gasification of fuelscontains naphthalene and cannot be completely freed therefrom by theordinary oil washing processes, because considerable quantities ofnaphthalene invariably remain in the gas. This residual naphthalenecontained in the gas is always a source of difficulty when 10 conveyingthe gas in tubular conduits and especially when the gas is to be forcedthrough the pipes under pressure for supplying places at a distance.Serious diificulties are occasioned by the constrictions or stoppings upwhich are produced by deposition of the naphthalene in the coolerportions of the pipes, and especially in circuits for conveying the gasto any distance.

Attempts have therefore been made to effect the complete removal of thenaphthalene from the gas. To this end it has been attempted to removethe naphthalene by adsorption agents of various kinds; and it also hasbeen thought that the naphthalene could be removed by super-cooling thegas. However, all these measures have hitherto not led to satisfactoryresults. Separating out the naphthalene by washing, by irrigation or byspraying with water has in a similar manner led to no satisfactoryresult.

It has now been found in accordance with the 80 present invention, thatit is possible to effect the complete removal of naphthalene from thegas by means of water, by spraying the water in a finely divided stateinto the current of gas, so that a perfect mist formation is obtained.The last traces of naphthalene can be removed from the gas by virtue ofthis precaution. It is important in this connection to cause the finemist to occupy the whole cross section of the washing pipe or tower. Thewater, the flow of which can be regulated by a pressure release valve,flows away and entrains the naphthalene, which latter is collected in aseparate container preferably provided with one or more thin layers ofsand, quartz or the like. The water thus freed from naphthalene can bere-employed for further washing operations.

It has also been observed that it is not necessary to maintain lowtemperatures of 15 C. or slightly above during the process:-Thus, whenthe temperature rises to C., an equally effective washing effect hasbeen obtained. It has thus been possible by means of the presentinvention, not only to effect the completeremoval of naphthalene fromthe gas with the cheapest of all washing agents. but to bring about thisaction with very small quantities of water, since after removing thenaphthalene from the water by a simple process of purification the saidwater is capable of repeated application. Moreover .the fact that theopera- 0 tion is independent of the maintenance of definite temperaturelimits is conducive of assuring an economical result.

In order to carry out the process a simple washing device is employed incombination with 5. nozzles by means of which a very fine mist formationcan be obtained. The washing tower or the washing tube is advantageouslychosen in such a manner that the washing process may also be carried outunder pressure. If the wash- 7o ing process is to be carried out underpressure then the dimensions of the washing'vessel may be madeconsiderably smaller.

Under some circumstances it is also of advantage to remove the bulk ofthe naphthalene in a 7 known manner with washing oils and to dispose ofthe residual remaining quantity by means of the finely divided spray ofwater. With this modification of the process it is possible to operatewith a very small quantity of water and further to reduce the erectingcosts of the plant as well as the operating costs.

The process according to the invention is carried out in a washing plantwhich is shown diagrammatically in the annexed drawing in which Figure 1is a vertical section and Figure 2 a top plan view of Figure 1. Thiswashing plant comprises three washing towers 1, 1a and 1b which areconnected in series, the requisite filters 2, 22 and 32 by means ofwhich the water used as a puri- .90 fying agent is freed from thenaphthalene and delivered to a collecting tank 3. The naphthalenecontaining gas enters at A, passes through the three washing towers byway of conduits '7 in the direction of the arrows and through regulatingvalve 8is discharged at B completely freed from naphthalene. The valve8a serves for re moving liquid-constituents. The washing out of thenaphthalene from the gas is effected by a fine water spray (indicated bysmall dots) covering the entire cross sectional area of the washingtowers 1, 1a and 1b which are sprayed through the nozzles fixed to therising pipe 5 and 5a. These nozzles are alternately arranged on bothsides in such a way as to prevent the intersection of the spraying conesand to render impossible the formation of drops. The water which ispresent in the atomized state is loaded with the naphthalene of the gasand collects on the bottom of the washing towers whence it flows offthrough the valves 8a and the water outlet .pipes 6 into the filters 2and from there into the collecting tank '3 subdivided into threecompartments. The

filters 2, 22 and 32 contain layers 2b of quartz or regulating the gasoutlet. -9 are water gauges.

indicating the level of the water that has collected on the bottom ofeach of the washing towers. Numeral 10 designates a gas outlet. cock ofthe pinch-cock type and is normally closed. Numerals 11 designatesbaflle plates. For attending to the various valves, etc., adiagrammatically drawn platform 12 is provided which may be reachedbymeans or the stairs 13.

I claim:-- a

1. A process for removing naphthalene from gases Whichcomprises washingoutv the naphthalene by means of a fine mist-dike spray of water at atemperature between 15 and C., passing the water through filter bedstofree it from naphthalene'andreturning it to the process.

2. A process'ior removing naphthalene from gases which comprises washingout the naph-- thalene by means of a fine mist-like spray of water at atemperature between. 15 and 40 0.,

passing the water through beds of sand to free it from naphthalene andreturning it to the process.

water, passing the water through beds of quartz to free'it fromnaphthalene and returning it to the process. 4

4. A process for removing naphthalene from.

gases which comprises treating the gases with washingoils, washing outthe residual naphthalene by means of a fine mist-like spray of water,

passing the water through filter beds to free it from naphthalene andreturning it to the process.

*5. A process for removing naphthalene from gases which comprisestreating the gases with washing oils, washing out the residualnaphthalene by means of a fine mist-like spray of water, passing thewater through beds of sand to free it from naphthalene and returning itto the process. v

6. A process forremoving naphthalene from gases which comprisestreatingthe gases with washing oils, washing out the residualnaphthalene by means of a fine mist-like spray of water, passing thewater through beds of quartz to free it from naphthalene and returningit to the process. I

7. A process for removing naphthalene from gases which comprises washingout the naphthalene by means of a fine mistlike spray or water.

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